U.S. patent application Ser. No. 516,503 filed Oct. 21, 1974 now U.S. Pat. No. 3,964,301 and U.S. patent application Ser. No. 569,857 filed Apr. 21, 1975 now U.S. Pat. No. 3,942,365 disclose means and method for determining brake torque, friction torque and indicated torque of engine type power plants. The mechanisms and methods described in those patent applications presuppose advance knowledge of the rotational moment of inertia of the engine power plant under test. The present invention discloses a method for power testing an engine power plant to determine its moment of inertia when moment of inertia information is unavailable from the power plant manufacturer.
The present invention contemplates the use of a dynamometer for applying predetermined loads on the engine during one of the test runs. However a feature of the invention is that the load-applying mechanism (dynamometer) is a low cost relatively small capacity unit. For example, the applied load need only be approximately 2 per cent of the engine torque capability. With a large engine of approximately 1000 horsepower rating the selected dynamometer could be a relatively small 20 horsepower unit. Such a unit possesses advantages in such respects as size, cost and convenience.